Datasheet LTC1545 Datasheet (Linear Technology)

FEATURES

■

Software-Selectable Transceiver Supports:
RS232, RS449, EIA530, EIA530-A, V.35, V.36, X.21

■

TUV/Detecon Inc. Certified NET1 and NET2
Compliant (Test Report No. NET2/071601/98)

■

TBR2 Compliant (Test Report No. CTR2/071601/98)

■

Software-Selectable Cable Termination Using
the LTC1344A

■

Complete DTE or DCE Port with LTC1543, LTC1344A

■

Operates from Single 5V Supply with LTC1543

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APPLICATIO S

■

Data Networking

■

CSU and DSU

■

Data Routers

LTC1545

Software-Selectable

Multiprotocol Transceiver

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DESCRIPTIO

The LTC®1545 is a 5-driver/5-receiver multiprotocol trans­ceiver. The LTC1545 and LTC1543 form the core of a
complete software-selectable DTE or DCE interface port that
supports the RS232, RS449, EIA530, EIA530-A, V.35, V.36
or X.21 protocols. Cable termination may be implemented
using the LTC1344A software-selectable cable termination
chip or by using existing discrete designs.

The LTC1545 runs from a 5V supply and the charge pump on
the LTC1543. The part is available in a 36-lead SSOP surface
mount package.

, LTC and LT are registered trademarks of Linear Technology Corporation.

TYPICAL APPLICATIO

DTE or DCE Multiprotocol Serial Interface with DB-25 Connector

LLRITMRL

D4D5

R3

CTS A (106)

CTS B

R2 R1

DSR A (109)

DSR B

R5

TM A (142)

RL A (140)

R4

LL A (141)

RI A (125)

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LTC1545

D3

DCD A (107)

DCD B

DTRDSR DCDCTS

D2 D1

DTR A (108)

DTR B

RTS

RTS B

RTS A (105)

SHIELD (101)

RXD B

SG (102)

RXCRXD

R2

RXC A (115)

RXC B

RXD A (104)

R1R3

LTC1543

D3

TXC A (114)

TXC B

D2

SCTE A (113)

SCTE B

TXDSCTETXC

D1

1424111512179314192062322513 81018*21 25 7 16

TXD A (103)

TXD B

LTC1344A

2

*OPTIONAL

DB-25 CONNECTOR

1545 TA01

1

LTC1545

WW

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ABSOLUTE MAXIMUM RATINGS

(Note 1)

Supply Voltage

VCC..................................................................... 6.5V

VEE........................................................ –10V to 0.3V

VDD....................................................... –0.3V to 10V

Input Voltage

Transmitters ........................... –0.3V to (VCC + 0.3V)

Receivers............................................... –18V to 18V

Logic Pins .............................. –0.3V to (VCC + 0.3V)

Output Voltage

Transmitters .................. (VEE – 0.3V) to (VDD + 0.3V)

Receivers................................ –0.3V to (VCC + 0.3V)

Short-Circuit Duration

Transmitter Output ..................................... Indefinite

Receiver Output.......................................... Indefinite

VEE.................................................................. 30 sec

Operating Temperature Range

LTC1545C .............................................. 0°C to 70°C

LTC1545I........................................... –40°C to 85°C

Storage Temperature Range ................ –65°C to 150°C

Lead Temperature (Soldering, 10 sec)................. 300°C

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PACKAGE/ORDER INFORMATION

TOP VIEW

V

1

CC

V

2

DD

D1

M0
M1
M2

DCE/DTE

D4ENB

R4EN

3

D2

4

D3

5

R1

6

R2

7

R3

8

D4

9

R4

10
11
12
13
14
15
16

R5

17

D5

18

T

JMAX

D1

D2

D3

R1

R2

R3

D4

R4

R5

D5

G PACKAGE

36-LEAD PLASTIC SSOP

= 150°C, θJA = 65°C/ W

Consult factory for Military grade parts.

36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19

V

EE

GND
D1 A
D1 B
D2 A
D2 B
D3/R1 A
D3/R1 B
R2 A
R2 B
R3 A
R3 B
D4 A
R4 A
R5 A
D5 A
V

DD

V

CC

ORDER PART

NUMBER

LTC1545CG
LTC1545IG

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ELECTRICAL CHARACTERISTICS

The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
VCC = 5V, VDD = 8V, VEE = – 7V for V.28, –5.5V for V.10, V.11 (Notes 2, 3)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Supplies

I

CC

I

EE

I

DD

P

D

VCC Supply Current (DCE Mode, RS530, RS530-A, X.21 Modes, No Load ● 2.7 5 mA
All Digital Pins = GND or V

) RS530, RS530-A, X.21 Modes, Full Load ● 110 150 mA

CC

V.28 Mode, No Load
V.28 Mode, Full Load
No-Cable Mode, D4ENB = HIGH

● 13 mA

● 13 mA

● 10 500 µA

VEE Supply Current (DCE Mode, RS530, RS530-A, X.21 Modes, No Load ● 2.0 4.0 mA
All Digital Pins = GND or V

) RS530, X.21 Modes, Full Load ● 23 35 mA

CC

RS530-A, Full Load
V.28 Mode, No Load
V.28 Mode, Full Load
No-Cable Mode, D4ENB = HIGH

● 34 50 mA

● 13 mA

● 12 18 mA

● 10 500 µA

VDD Supply Current (DCE Mode, RS530, RS530-A, X.21 Modes, NoLoad ● 0.3 2 mA
All Digital Pins = GND or V

) RS530, RS530-A, X.21 Modes, Full Load ● 0.3 2 mA

CC

V.28 Mode, No Load
V.28 Mode, Full Load
No-Cable Mode, D4ENB = HIGH

● 13 mA

● 13.5 18 mA

● 10 500 µA

Internal Power Dissipation (DCE Mode, RS530, RS530-A, X.21 Modes, Full Load 340 mW
(All Digital Pins = GND or V

) V.28 Mode, Full Load 64 mW

CC

2

LTC1545

ELECTRICAL CHARACTERISTICS

The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
VCC = 5V, VDD = 8V, VEE = – 7V for V.28, –5.5V for V.10, V.11 (Notes 2, 3)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Logic Inputs and Outputs

V

IH

V

IL

I

IN

V

OH

V

OL

I

OSR

I

OZR

V.11 Driver

V

ODO

V

ODL

∆V

V

OC

∆V

I

SS

I

OZ

tr, t

t

PLH

t

PHL

∆t Input to Output Difference, t

t

SKEW

V.11 Receiver

V

TH

∆V
I

IN

R

IN

tr, t
t

PLH

t

PHL

∆t Input to Output Difference, t

Logic Input High Voltage ● 2V
Logic Input Low Voltage ● 0.8 V
Logic Input Current D1, D2, D3, D4, D5 ● ±10 µA

M0, M1, M2, DCE, D4ENB, R4EN = GND (LTC1545C) ● –100 –50 – 30 µA
M0, M1, M2, DCE, D4ENB, R4EN = GND (LTC1545I) ● –120 –50 – 30 µA
M0, M1, M2, DCE, D4ENB, R4EN = V

CC

● ±10 µA

Output High Voltage IO = –4mA ● 3 4.5 V
Output Low Voltage IO = 4mA ● 0.3 0.8 V
Output Short-Circuit Current 0V ≤ VO ≤ V

CC

Three-State Output Current M0 = M1 = M2 = VCC, 0V ≤ VO ≤ V

CC

● –50 40 50 mA

±1 µA

Open Circuit Differential Output Voltage RL = 1.95k (Figure 1) ● ±5V
Loaded Differential Output Voltage RL = 50Ω (Figure 1) 0.5V

ODO

0.67V

ODO

RL = 50Ω (Figure 1) ● ±2V

Change in Magnitude of Differential RL = 50Ω (Figure 1) ● 0.2 V

OD

Output Voltage
Common Mode Output Voltage RL = 50Ω (Figure 1) ● 3V
Change in Magnitude of Common Mode RL = 50Ω (Figure 1) ● 0.2 V

OC

Output Voltage
Short-Circuit Current V

= GND ±150 mA

OUT

Output Leakage Current –0.25V ≤ VO ≤ 0.25V, Power Off or ● ±1 ±100 µA

No-Cable Mode or Driver Disabled

Rise or Fall Time LTC1545C (Figures 2, 5) ● 21525 ns

f

LTC1545I (Figures 2, 5) ● 21535 ns

Input to Output LTC1545C (Figures 2, 5) ● 20 40 65 ns

LTC1545I (Figures 2, 5) ● 20 40 75 ns

Input to Output LTC1545C (Figures 2, 5) ● 20 40 65 ns

LTC1545I (Figures 2, 5) ● 20 40 75 ns

– t

PLH

 LTC1545C (Figures 2, 5) ● 0312 ns

PHL

LTC1545I (Figures 2, 5) ● 0317 ns

Output to Output Skew (Figures 2, 5) 3 ns

Input Threshold Voltage –7V ≤ VCM ≤ 7V ● –0.2 0.2 V
Input Hysteresis –7V ≤ VCM ≤ 7V ● 15 40 mV

TH

Input Current (A, B) –10V ≤ V
Input Impedance –10V ≤ V
Rise or Fall Time (Figures 2, 6) 15 ns

f

≤ 10V ● ±0.66 mA

A,B

≤ 10V ● 15 30 kΩ

A,B

Input to Output LTC1545C (Figures 2, 6) ● 50 80 ns

LTC1545I (Figures 2, 6) ● 50 90 ns

Input to Output LTC1545C (Figures 2, 6) ● 50 80 ns

LTC1545I (Figures 2, 6) ● 50 90 ns

– t

PLH

 LTC1545C (Figures 2, 6) ● 0416 ns

PHL

LTC1545I (Figures 2, 6) ● 0421 ns

3

LTC1545

ELECTRICAL CHARACTERISTICS

The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
VCC = 5V, VDD = 8V, VEE = – 7V for V.28, –5.5V for V.10, V.11 (Notes 2, 3)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V.10 Driver

V

O

V

T

I

SS

I

OZ

tr, t

f

t

PLH

t

PHL

V.10 Receiver

V

TH

∆V

TH

I

IN

R

IN

tr, t

f

t

PLH

t

PHL

∆t Input to Output Difference, t

V.28 Driver

V

O

I

SS

I

OZ

SR Slew Rate RL = 3k, CL = 2500pF (Figures 3, 7) ● 430V/µs
t

PLH

t

PHL

V.28 Receiver

V

THL

V

TLH

∆V

TH

R

IN

tr, t

f

t

PLH

t

PHL

Output Voltage Open Circuit, RL = 3.9k ● ±4 ±6V
Output Voltage RL = 450Ω (Figure 3) ● ±3.6 V

= 450Ω (Figure 3) 0.9V

R

L

O

Short-Circuit Current VO = GND ±150 mA
Output Leakage Current –0.25V ≤ VO ≤ 0.25V, Power Off or ● ±0.1 ±100 µA

No-Cable Mode or Driver Disabled
Rise or Fall Time RL = 450Ω, CL = 100pF (Figures 3, 7) 2 µs
Input to Output RL = 450Ω, CL = 100pF (Figures 3, 7) 1 µs
Input to Output RL = 450Ω, CL = 100pF (Figures 3, 7) 1 µs

Receiver Input Threshold Voltage ● –0.25 0.25 V
Receiver Input Hysteresis ● 25 50 mV
Receiver Input Current –10V ≤ VA ≤ 10V ● ±0.66 mA
Receiver Input Impedance –10V ≤ VA ≤ 10V ● 15 30 kΩ
Rise or Fall Time (Figures 4, 8) 15 ns
Input to Output (Figures 4, 8) 55 ns
Input to Output (Figures 4, 8) 109 ns

– t

PLH

 (Figures 4, 8) 60 ns

PHL

Output Voltage Open Circuit ● ±10 V

R

= 3k (Figure 3) ● ±5 ±8.5 V

L

Short-Circuit Current VO = GND ● ±150 mA
Output Leakage Current –0.25V ≤ VO ≤ 0.25V, Power Off or ● ±1 ±100 µA

No-Cable Mode or Driver Disabled

Input to Output RL = 3k, CL = 2500pF (Figures 3, 7) ● 1.3 2.5 µs
Input to Output RL = 3k, CL = 2500pF (Figures 3, 7) ● 1.3 2.5 µs

Input Low Threshold Voltage ● 1.5 0.8 V
Input High Threshold Voltage ● 2 1.6 V
Receiver Input Hysterisis ● 0.1 0.3 V
Receiver Input Impedance –15V ≤ VA ≤ 15V ● 357 kΩ
Rise or Fall Time (Figures 4, 8) 15 ns
Input to Output (Figures 4, 8) ● 60 100 ns
Input to Output (Figures 4, 8) ● 150 450 ns

Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.

Note 2: All currents into device pins are positive; all currents out of device
are negative. All voltages are referenced to device ground unless otherwise
specified.

4

Note 3: All typicals are given for V
–5.5V for V.10, V.11 and T

= 25°C.

A

= 5V, VDD = 8V, VEE = –7V for V.28,

CC

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PIN FUNCTIONS

LTC1545

VCC (Pins 1, 19): Positive Supply for the Transceivers.

4.75V ≤ VCC ≤ 5.25V. Connect a 1µF capacitor to ground.
VDD (Pins 2, 20): Positive Supply Voltage for V.28. Con-

nect to VDD Pin 3 on LTC1543 or 8V supply. Connect a 1µF
capacitor to ground.

D1 (Pin 3): TTL Level Driver 1 Input.
D2 (Pin 4): TTL Level Driver 2 Input.
D3 (Pin 5): TTL Level Driver 3 Input.
R1 (Pin 6): CMOS Level Receiver 1 Output.
R2 (Pin 7): CMOS Level Receiver 2 Output.
R3 (Pin 8): CMOS Level Receiver 3 Output.
D4 (Pin 9): TTL Level Driver 4 Input.
R4 (Pin 10): CMOS Level Receiver 4 Output.
M0 (Pin 11): TTL Level Mode Select Input 0 with Pull-Up

to VCC.
M1 (Pin 12): TTL Level Mode Select Input 1 with Pull-Up

to VCC.

R5 (Pin 17): CMOS Level Receiver 5 Output.
D5 (Pin 18): TTL Level Driver 5 Input.
D5 A (Pin 21): Driver 5 Output.
R5 A (Pin 22): Receiver 5 Input.
R4 A (Pin 23): Receiver 4 Input.
D4 A (Pin 24): Driver 4 Input.
R3 B (Pin 25): Receiver 3 Noninverting Input.
R3 A (Pin 26): Receiver 3 Inverting Input.
R2 B (Pin 27): Receiver 2 Noninverting Input.
R2 A (Pin 28): Receiver 2 Inverting Input.
D3/R1 B (Pin 29): Receiver 1 Noninverting Input and

Driver 3 Noninverting Output.
D3/R1 A (Pin 30): Receiver 1 Inverting Input and Driver 3

Inverting Output.

D2 B (Pin 31): Driver 2 Noninverting Output.
D2 A (Pin 32): Driver 2 Inverting Output.

M2 (Pin 13): TTL Level Mode Select Input 2 with Pull-Up

to VCC.
DCE/DTE (Pin 14): TTL Level Mode Select Input with

Pull-Up to VCC. Logic high enables Driver 3. Logic low
enables Receiver 1.

D4ENB (Pin 15): TTL Level Enable Input with Pull-Up to
VCC. Logic low enables Driver 4.

R4EN (Pin 16): TTL Level Enable Input with Pull-Up to VCC.
Logic high enables Receiver 4.

TEST CIRCUITS

A

R

L

V

OD

V

OC

R

L

B

1545 F01

D1 B (Pin 33): Driver 1 Noninverting Output.
D1 A (Pin 34): Driver 1 Inverting Output.
GND (Pin 35): Ground.
V

(Pin 36): Negative Supply Voltage. Connect to VEE Pin

EE

26 on LTC1543. Connect a 1µF capacitor to ground.

C

L

B

R

L

100Ω

A

100pF

C
100pF

B

R

L

A

15pF

1545 F02

Figure 1. V.11 Driver Test Circuit Figure 2. V.11 Driver/Receiver AC Test Circuit

5

LTC1545

TEST CIRCUITS

W

D

A

R

C

L

L

1545 F03

Figure 3. V.10/V.28 Driver Test Circuit

U

D

Figure 4. V.10/V.28 Receiver Test Circuit

A

A

R

15pF

1545 F04

ODE SELECTIO

(Note 1) (Note 2) (Note 1) (Note 3)

LTC1545 MODE NAME M2 M1 M0 D1 D2 D3 D4 D5 R1 R2 R3 R4 R5

Not Used (Default V.11) 0 0 0 V.11 V.11 V.11 V.10 V.10 V.11 V.11 V.11 V.10 V.10
RS530A 0 0 1 V.11 V.10 V.11 V.10 V.10 V.11 V.10 V.11 V.10 V.10
RS530 0 1 0 V.11 V.11 V.11 V.10 V.10 V.11 V.11 V.11 V.10 V.10
X.21 0 1 1 V.11 V.11 V.11 V.10 V.10 V.11 V.11 V.11 V.10 V.10
V.35 1 0 0 V.28 V.28 V.28 V.28 V.28 V.28 V.28 V.28 V.28 V.28
RS449/V.36 1 0 1 V.11 V.11 V.11 V.10 V.10 V.11 V.11 V.11 V.10 V.10
V.28/RS232 1 1 0 V.28 V.28 V.28 V.28 V.28 V.28 V.28 V.28 V.28 V.28
D4ENB = 1, R4EN = 0 111ZZZZZZZZZZ

M0 = M1 = M2 = 1
Note 1: Driver 3 and Receiver 1 are enabled (and disabled) by

DCE/DTE (Pin 14). Logic high enables Driver 3. Logic low enables
Receiver 1.

Note 2: Driver 4 is enabled by D4ENB = 0 (Pin 15).
Note 3: Receiver 4 is enabled by R4EN = 1 (Pin 16).

UWW

SWITCHI G TI E WAVEFOR S

B – A

5V

D

0V

V

O

–V

O

A

B

V

O

1.5V 1.5V

t

PLH

50%

90%

10%

t

r

t

SKEW

f = 1MHz : tr ≤ 10ns : tf ≤ 10ns

V

DIFF

1/2 V

O

Figure 5. V.11 Driver Propagation Delays

6

= V(B) – V(A)

t

PHL

90%

50%

10%

t

f

t

SKEW

1545 F05

UWW

SWITCHI G TI E WAVEFOR S

V

B – A

–V

OD2

OD2

V

OH

R

V

OL

0V

t

PLH

1.5V

Figure 6. V.11 Receiver Propagation Delays

f = 1MHz : tr ≤ 10ns : tf ≤ 10ns

INPUT

OUTPUT

LTC1545

0V

t

PHL

1.5V

1545 F06

3V

D

0V

V

O

A

–V

O

1.5V

t

PHL

3V

0V

–3V

t

f

Figure 7. V.10, V.28 Driver Propagation Delays

V

IH

A

V

IL

V

OH

R

V

OL

1.5V

t

PHL

1.5V

Figure 8. V.10, V.28 Receiver Propagation Delays

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APPLICATIONS INFORMATION

Overview

Mode Selection

1.5V

1.5V

–3V

t

PLH

t

PLH

0V

3V

t

r

1.5V

1545 F07

1545 F08

The LTC1543/LTC1545 form the core of a complete soft­ware-selectable DTE or DCE interface port that supports
the RS232, RS449, EIA530, EIA530-A, V.35, V.36 or X.21
protocols. Cable termination may be implemented using
the LTC1344A software-selectable cable termination chip
or by using existing discrete designs.

A complete DCE-to-DTE interface operating in EIA530
mode is shown in Figure 9. The LTC1543 of each port is
used to generate the clock and data signals. The LTC1545
is used to generate the control signals along with LL (Local
Loop-Back), RL (Remote Loop-Back), TM (Test Mode)
and RI (Ring Indicate). The LTC1344A cable termination
chip is used only for the clock and data signals because
they must support V.35 cable termination. The control
signals do not need any external resistors.

The interface protocol is selected using the mode select
pins M0, M1 and M2 (see the Mode Selection table).

For example, if the port is configured as a V.35 interface,
the mode selection pins should be M2 = 1, M1 = 0, M0 = 0.
For the control signals, the drivers and receivers will
operate in V.28 (RS232) electrical mode. For the clock and
data signals, the drivers and receivers will operate in V.35
electrical mode. The DCE/DTE pin will configure the port
for DCE mode when high, and DTE when low.

The interface protocol may be selected simply by plugging
the appropriate interface cable into the connector. The
mode pins are routed to the connector and are left uncon­nected (1) or wired to ground (0) in the cable as shown in
Figure 10.

7

LTC1545

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APPLICATIONS INFORMATION

SERIAL

CONTROLLER

SCTE

RXC

RXD

RTS

TXD

TXC

LTC1543

D1

D2

D3

R1

R2

R3

LTC1545

D1

LTC1344A

103Ω

103Ω

103Ω

TXD

SCTE

TXC

RXC

RXD

RTS

LTC1344A

103Ω

103Ω

DCEDTE

LTC1543

R3

R2

R1

LTC1545

R3

SERIAL

CONTROLLER

TXD

SCTE

D3

D2

D1

TXC

RXC

RXD

RTS

DTR

DCD

DSR

CTS

TM

D2

D3

R1

R2

R3

LL

RI

RL

D4

R4

R5

D5

DTR

DCD

DSR

CTS

TM

Figure 9. Complete Multiprotocol Interface in EIA530 Mode

The internal pull-up current sources will ensure a binary 1
when a pin is left unconnected and that the LTC1543/
LTC1545 and the LTC1344A enter the no-cable mode
when the cable is removed. In the no-cable mode the
LTC1543/LTC1545 supply current drops to less than
200µA and all LTC1543/LTC1545 driver outputs and
LTC1344A resistive terminations are forced into a high
impedance state.

R2

R1

D3

D2

D1

LL

RI

RL

R4

D4

D5

R5

DTR

DCD

DSR

CTS

LL

TM

RI

RL

1545 F09

The mode selection may also be accomplished by using
jumpers to connect the mode pins to ground or VCC.

Cable Termination

Traditional implementations have included switching
resistors with expensive relays, or required the user to
change termination modules every time the interface
standard has changed. Custom cables have been used

8

LTC1545

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APPLICATIONS INFORMATION

LTC1344A

DCE/

LTC1543

LTC1545

(DATA)

M0

M1

M2

DCE/DTE

DCE/DTE

M2

M1

M0

D4ENB

R4EN

M2 M1

DTE

22

11

12

13

14

14

13

12

11

15

16

M0 (DATA)

23 24 1

LATCH

21

CONNECTOR

NC

NC

CABLE

10k

V

CC

(DATA)

Figure 10: Single Port DCE V.35 Mode Selection in the Cable

with the termination in the cable head or separate termina­tions are built on the board and a custom cable routes the
signals to the appropriate termination. Switching the
terminations with FETs is difficult because the FETs must
remain off even though the signal voltage is beyond the
supply voltage for the FET drivers or the power is off.

Using the LTC1344A along with the LTC1543/LTC1545
solves the cable termination switching problem. Via soft­ware control, the LTC1344A provides termination for the
V.10 (RS423), V.11 (RS422), V.28 (RS232) and V.35
electrical protocols.

V.10 (RS423) Interface

A typical V.10 unbalanced interface is shown in Figure 11.
A V.10 single-ended generator output A with ground C is
connected to a differential receiver with inputs A' con­nected to A, and input C' connected to the signal return
ground C. Usually, no cable termination is required for
V.10 interfaces, but the receiver inputs must be compliant
with the impedance curve shown in Figure 12.

1545 F10

The V.10 receiver configuration in the LTC1545 is shown
in Figure 13. In V.10 mode switch S3 inside the LTC1545
is turned off. The noninverting input is disconnected
inside the LTC1545 receiver and connected to ground.The
cable termination is then the 30k input impedance to
ground of the LTC1545 V.10 receiver.

V.11 (RS422) Interface

A typical V.11 balanced interface is shown in Figure 14. A
V.11 differential generator with outputs A and B with
ground C is connected to a differential receiver with
ground C', inputs A' connected to A, B' connected to B. The
V.11 interface has a differential termination at the receiver
end that has a minimum value of 100Ω. The termination
resistor is optional in the V.11 specification, but for the
high speed clock and data lines, the termination is required
to prevent reflections from corrupting the data. The
receiver inputs must also be compliant with the imped­ance curve shown in Figure 12.

9

LTC1545

R3

124Ω

R5

20k

LTC1344A

LTC1543
LTC1545

RECEIVER

1545 F15

A

B

A

'

B

'

C

'

R1

51.5Ω

R8
6k

S2

S3

R2

51.5Ω

R6
10k

R7
10k

GND

R4

20k

S1

AA'

B

C

B'

C'

GENERATOR

BALANCED

INTERCONNECTING

CABLE

LOAD

CABLE

TERMINATION

RECEIVER

100Ω
MIN

1545 F14

U

WUU

APPLICATIONS INFORMATION

BALANCED

GENERATOR

–10V

INTERCONNECTING

CABLE

TERMINATION

AA

CC

'

'

Figure 11. Typical V.10 Interface

I

Z

–3V

3V 10V

LOAD

CABLE

RECEIVER

1545 F11

3.25mA

V

Z

Figure 14. Typical V.11 Interface

–3.25mA

Figure 12. V.10 Receiver Input Impedance

A

'

B

'

C

'

Figure 13. V.10 Receiver Configuration

10

A

B

R8
6k

S3

GND

R5

20k

R4

20k

R6
10k

R7
10k

LTC1545

RECEIVER

1545 F13

1545 F12

Figure 15. V.11 Receiver Configuration

In V.11 mode, all switches are off except S1 inside the
LTC1344A which connects a 103Ω differential termina­tion impedance to the cable as shown in Figure 15.

V.28 (RS232) Interface

A typical V.28 unbalanced interface is shown in Figure 16.
A V.28 single-ended generator output A with ground C is
connected to a single-ended receiver with input A' con­nected to A, ground C' connected via the signal return
ground C.

In V.28 mode, all switches are off except S3 inside the
LTC1543/LTC1545 which connects a 6k (R8) impedance
to ground in parallel with 20k (R5) plus 10k (R6) for a
combined impedance of 5k as shown in Figure 17. The
noninverting input is disconnected inside the LTC1543/
LTC1545 receiver and connected to a TTL level reference
voltage for a 1.4V receiver trip point.

LTC1545

R3

124Ω

R5

20k

LTC1344A

LTC1543

RECEIVER

1545 F19

A

B

A

'

B

'

C

'

R1

51.5Ω

R8
6k

S2

S3

R2

51.5Ω

R6
10k

R7
10k

GND

R4
20k

S1

U

WUU

APPLICATIONS INFORMATION

BALANCED

GENERATOR

'

A

B

'

C

'

INTERCONNECTING

CABLE

AA

CC

Figure 16. Typical V.28 Interface

A

LTC1344A

R1

51.5Ω

S1

S2

R2

51.5Ω

R3

124Ω

R8
6k

S3

B

GND

TERMINATION

'

'

R5
20k

R4

20k

CABLE

R6
10k

R7
10k

LOAD

RECEIVER

LTC1543
LTC1545

RECEIVER

1545 F16

V.35 interface requires a T or delta network termination at
the receiver end and the generator end. The receiver
differential impedance measured at the connector must be
100Ω␣ ±10Ω, and the impedance between shorted termi­nals (A' and B') and ground C' must be 150Ω ±15Ω.

In V.35 mode, both switches S1 and S2 inside the LTC1344A
are on, connecting the T network impedance as shown in
Figure 19. Both switches in the LTC1543 are off. The 30k
input impedance of the receiver is placed in parallel with
the T network termination, but does not affect the overall
input impedance significantly.

The generator differential impedance must be 50Ω to
150Ω and the impedance between shorted terminals (A
and B) and ground C must be 150Ω ±15Ω. For the
generator termination, switches S1 and S2 are both on and
the top side of the center resistor is brought out to a pin so
it can be bypassed with an external capacitor to reduce
common mode noise as shown in Figure 20.

1545 F17

Figure 17. V.28 Receiver Configuration

BALANCED

INTERCONNECTING

A

B

C

CABLE

CABLE

TERMINATION

A

'

125Ω

'

B

C

'

LOAD

50Ω

50Ω

RECEIVER

1545 F18

Figure 19. V.35 Receiver Configuration

V.35 DRIVER

LTC1344A

124Ω

ON

C1
100pF

51.5Ω

S1

S2

ON

51.5Ω

1545 F20

Figure 20. V.35 Driver Using the LTC1344A

A

B

C

11

GENERATOR

50Ω

125Ω

50Ω

Figure 18. Typical V.35 Interface

V.35 Interface

A typical V.35 balanced interface is shown in Figure 18. A
V.35 differential generator with outputs A and B with
ground C is connected to a differential receiver with
ground C', inputs A' connected to A, B' connected to B. The

LTC1545

U

WUU

APPLICATIONS INFORMATION

Any mismatch in the driver rise and fall times or skew in
the driver propagation delays will force current through
the center termination resistor to ground, causing a high
frequency common mode spike on the A and B terminals.
The common mode spike can cause EMI problems that are
reduced by capacitor C1 which shunts much of the com­mon mode energy to ground rather than down the cable.

No-Cable Mode

The no-cable mode (M0 = M1 = M2 = D4ENB = 1, R4EN = 0)
is intended for the case when the cable is disconnected
from the connector. The charge pump, bias circuitry,
drivers and receivers are turned off, the driver outputs are
forced into a high impedance state, and the supply current
drops to less than 200µA.

Charge Pump

The LTC1543 uses an internal capacitive charge pump to
generate VDD and VEE as shown in Figure 21. A voltage
doubler generates about 8V on VDD and a voltage inverter
generates about – 7.5V for VEE. Four 1µF surface mounted
tantalum or ceramic capacitors are required for C1, C2, C3
and C4. The VEE capacitor C5 should be a minimum of

3.3µF. All capacitors are 16V and should be placed as close
as possible to the LTC1543 to reduce EMI. The turn-on
time for the charge pump is 60ms.

3

V

C3
1µF

5V

DD

2

+

C1

C1
1µF

C4
1µF

Figure 21. Charge Pump

LTC1543

1

–

C1

4

V

CC

Receiver Fail-Safe

All LTC1543/LTC1545 receivers feature fail-safe opera­tion in all modes. If the receiver inputs are left floating or
shorted together by a termination resistor, the receiver
output will always be forced to a logic high.

C2

C2

V

GND

28

+

27

–

26

EE

25

C2
1µF

C5

+

3.3µF

1545 F21

DTE vs DCE Operation

The DCE/DTE pin acts as an enable for Driver 3/Receiver
1 in the LTC1543, and Driver 3/Receiver 1 in the LTC1545.

The LTC1543/LTC1545 can be configured for either DTE
or DCE operation in one of two ways: a dedicated DTE or
DCE port with a connector of appropriate gender, or a port
with one connector that can be configured for DTE or DCE
operation by rerouting the signals to the LTC1543/LTC1545
using a dedicated DTE cable or dedicated DCE cable.

A dedicated DTE port using a DB-25 male connector is
shown in Figure 22. The interface mode is selected by logic
outputs from the controller or from jumpers to either V

CC

or GND on the mode select pins. A dedicated DCE port
using a DB-25 female connector is shown in Figure 23.

A port with one DB-25 connector, can be configured for
either DTE or DCE operation is shown in Figure 24. The
configuration requires separate cables for proper signal
routing in DTE or DCE operation. For example, in DTE
mode, the TXD signal is routed to Pins 2 and 14 via Driver
1 in the LTC1543. In DCE mode, Driver 1 now routes the
RXD signal to Pins 2 and 14.

Compliance Testing

A European standard EN 45001 test report is available for
the LTC1343/LTC1545/LTC1344A chipset. A copy of the
test report is available from LTC or TUV Telecom Services
Inc. (formerly Detecon Inc.)

The title of the report is:
Test Report No. NET2/071601/98.
The address of TUV Telecom Services Inc. is:
TUV Telecom Services Inc.

Suite 107
1775 Old Highway 8
St. Paul, MN 55112 USA
Tel. [phone]
Fax. [phone]

12

U

TYPICAL APPLICATIONS

V

CC

5V

3

TXD

SCTE

C3
1µF

1µF

1

C1

C5
1µF

CHARGE

2

PUMP

4

LTC1543

5

D1

6

D2

7

D3

LTC1545

C6

100pFC7100pF

3 8 11 12 13

V

CC

28

C2
1µF

27
26

C4

+

3.3µF

25

24
23

22
21

C13
1µF

C12
1µF

2

V

EE

5

C8

100pF

16109764

15 18 17 19 20 22

LTC1344A

LATCH

DCE/DTEM2M1

23 24141

21

M0

2

TXD A (103)

14

TXD B

24

SCTE A (113)

11

SCTE B

C10
1µF

TXC

RXC

RXD

RTS

DTR

DCD

DSR

CTS

R4

GND

R5

D4ENB

R4EN

20
19
18
17
16
15

36

V

EE

35

34
33

32
31

30
29
28
27

26
25
24

23

22

21

15

16

C11
1µF

NC

8

R1

9

R2

10

R3

11

M0

12

M1

13

M2

14

DCE/DTE

V

CC

5V

C9

1,19

1µF

LL

RI

TM

RL

M0
M1
M2

2,20

10

17

18

11
12
13
14

3

4

5

6

7

8

9

V

CC

V

DD

LTC1545

M0
M1
M2
DCE/DTE

D1

D2

D3

R1

R2

R3

D4

D5

15
12
17

9

3

16

7

1

4

19
20

23

8

10

6

22

5
13
18

*

25

21

*OPTIONAL

1544 F22

TXC A (114)
TXC B
RXC A (115)
RXC B
RXD A (104)
RXD B

SG

SHIELD

DB-25 MALE
CONNECTOR

RTS A (105)
RTS B
DTR A (108)
DTR B

DCD A (109)
DCD B
DSR A (107)
DSR B
CTS A (106)
CTS B
LL (141)

RI (125)

TM (142)

RL (140)

Figure 22. Controller-Selectable Multiprotocol DTE Port with DB-25 Connector

13

LTC1545

TYPICAL APPLICATIONS

V

CC

5V

3

RXD

RXC

C3
1µF

1µF

1

C1

C5
1µF

CHARGE

2

PUMP

4

LTC1543

5

D1

6

D2

7

D3

U

C6

100pFC7100pF

3 8 11 12 13

V

CC

28

C2
1µF

27
26

C4

+

3.3µF

25

24
23

22
21

C13
1µF

C12
1µF

2

V

EE

5

C8

100pF

16109764

15 18 17 19 20 22

LTC1344A

DCE/DTEM2M1

V

CC

LATCH

23 24141

21

M0

3

RXD A (104)

16

RXD B

17

RXC A (115)

9

RXC B

C10
1µF

TXC

SCTE

TXD

CTS

DSR

DCD

DTR

RTS

R4

V

GND

R5

D4ENB

R4EN

20
19
18
17
16
15

36

EE

35

34
33

32
31

30
29
28
27

26
25
24

23

22

21

15

16

C11
1µF

NC

8

R1

9

R2

10

R3

11

M0

12

M1

13

M2

14

DCE/DTE

NC

V

CC

5V

RI

LL

RL

TM

M0
M1
M2

C9
1µF

1,19

V

CC

2,20

V

DD

3

D1

4

D2

5

D3

LTC1545

6

R1

7

R2

8

R3

9

D4

10

17

18

D5

11

M0

12

M1

13

M2

14

NC

DCE/DTE

15
12
24

11

2

14

7

1

5

13

6

22

8
10
20
23

4
19

*

18

21

25

*OPTIONAL

1544 F23

TXC A (114)
TXC B
SCTE A (113)
SCTE B
TXD A (103)
TXD B

SGND (102)

SHIELD (101)

DB-25 FEMALE

CONNECTOR

CTS A (106)
CTS B
DSR A (107)
DSR B

DCD A (109)
DCD B
DTR A (108)
DTR B
RTS A (105)
RTS B
RI (125)

LL (141)

RL (140)

TM (142)

Figure 23. Controller-Selectable DCE Port with DB-25 Connector

14

U

TYPICAL APPLICATIONS

V

CC

5V

3

DTE_TXD/DCE_RXD

DTE_SCTE/DCE_RXC

C3
1µF

1µF

1

C1

C5
1µF

CHARGE

2
4

LTC1543

5

6

D2

7

D3

PUMP

D1

LTC1545

C6

100pFC7100pF

3 8 11 12 13

V

CC

28

C2
1µF

27
26

C4

+

3.3µF

25

24
23

22
21

C13
1µF

C12
1µF

2

V

EE

C8

100pF

LTC1344A

21

LATCH

DCE/DTEM2M1

5

16109764

15 18 17 19 20 22

23 24141

M0

DTE DCE

2

TXD A

14

TXD B

24

SCTE A

11

SCTE B

RXD A
RXD B
RXC A
RXC B

DTE_TXC/DCE_TXC

DTE_RXC/DCE_SCTE

DTE_RXD/DCE_TXD

C10
1µF

DTE_RTS/DCE_CTS

DTE_DTR/DCE_DSR

DTE_DCD/DCE_DCD

DTE_DSR/DCE_DTR

DTE_CTS/DCE_RTS

DTE_LL/DCE_RI

DTE_RI/DCE_LL

DTE_TM/DCE_RL

DTE_RL/DCE_TM

DCE/DTE

8

9

10
11

M0

12

M1

13

M2

14

DCE/DTE

V

CC

5V

C9

1,19

1µF

M0
M1
M2

2,20

10

17

18

11
12
13
14

3

4

5

6

7

8

9

V

CC

V

DD

LTC1545

M0
M1
M2
DCE/DTE

D1

D2

D3

D4

D5

20

R1

19
18

R2

17
16

R3

15

36

V

EE

35

GND

34
33

32
31

30

R1

29
28

R2

27
26

R3

25
24

23

R4

22

R5

21

15

D4ENB

16

R4EN

C11
1µF

NC

15
12
17

9

3

16

7

1

4

19
20

23

8

10

6

22

5

13

18

*

25

21

*OPTIONAL

1544 F24

TXC A

TXC B
RXC A
RXC B
RXD A
RXD B

SG

SHIELD

CONNECTOR

RTS A
RTS B
DTR A
DTR B

DCD A

DCD B
DSR A

DSR B
CTS A
CTS B

LL

RI

RL

TXC A
TXC B
SCTE A
SCTE B
TXD A
TXD B

DB-25

CTS A
CTS B
DSR A
DSR B

DCD A
DCD B

DTR A
DTR B

RTS A
RTS B
RI

LL

RLTM

TM

Figure 24. Controller-Selectable Multiprotocol DTE/DCE Port with DB-25 Connector

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen­tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

15

LTC1545

PACKAGE DESCRIPTION

5.20 – 5.38**
(0.205 – 0.212)

U

Dimensions in inches (millimeters) unless otherwise noted.

G Package

36-Lead Plastic SSOP (0.209)

(LTC DWG # 05-08-1640)

12.67 – 12.93*
(0.499 – 0.509)

2526 22 21 20 19232427282930313233343536

7.65 – 7.90

(0.301 – 0.311)

12345678 9 10 11 12 14 15 16 17 1813

1.73 – 1.99

(0.068 – 0.078)

° – 8°

0

0.13 – 0.22

(0.005 – 0.009)

NOTE: DIMENSIONS ARE IN MILLIMETERS

*

DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.152mm (0.006") PER SIDE

**

DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.254mm (0.010") PER SIDE

0.55 – 0.95

(0.022 – 0.037)

0.65

(0.0256)

BSC

0.25 – 0.38

(0.010 – 0.015)

0.05 – 0.21

(0.002 – 0.008)

G36 SSOP 1098

RELATED PARTS

PART NUMBER DESCRIPTION COMMENTS

LTC1321 Dual RS232/RS485 Transceiver Two RS232 Driver/Receiver Pairs or Two RS485 Driver/Receiver Pairs
LTC1322 Dual RS232/RS485 Transceiver Four RS232 Driver/Receiver Pairs or Two RS485 Driver/Receiver Pairs
LTC1334 Single 5V RS232/RS485 Multiprotocol Transceiver Two RS232 Driver/Receiver Pairs or Four RS232 Driver/Receiver Pairs
LTC1335 Dual RS232/RS485 Transceiver Four RS232 Driver/Receiver Pairs or Two RS485 Driver/Receiver Pairs
LTC1343 Software-Selectable Multiprotocol Transceiver 4-Driver/4-Receiver for Data and Clock Signals
LTC1344A Software-Selectable Cable Terminator Perfect for Terminating the LTC1543
LTC1345 Single Supply V.35 Transceiver 3-Driver/3-Receiver for Data and Clock Signals
LTC1346A Dual Supply V.35 Transceiver 3-Driver/3-Receiver for Data and Clock Signals
LTC1543 Software-Selectable Multiprotocol Transceiver Companion to LTC1544/LTC1545 for Data and Clock Signals
LTC1544 Software-Selectable Multiprotocol Transceiver 4-Driver/4-Receiver for Control Signals
LTC1387 Single 5V RS232/RS485 Multiprotocol Transceiver Two RS232 Driver/Receiver Pairs or One RS485 Driver/Receiver Pair

16

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

[phone] ● FAX: [phone]

●

www.linear-tech.com

1545fa LT/TP 1199 2K REV A • PRINTED IN USA

 LINEAR TECHNOLOGY CORPORATION 1998